Conventionally, as a drive device for performing a single directional reciprocal linear motion by using a hollow motor, there is known, for example, a drive device disclosed in the following Patent Publication 1. In this drive device, a driven rod is disposed in a manner of penetrating an inner hollow portion of the hollow motor, and a rotating motion of a tubular rotor forming the hollow portion is transmitted as a linear driving force of the driven rod. More specifically, a female thread is formed to an inner peripheral surface of the rotor and a male thread capable of being screw-engaged with the female thread is formed to an outer peripheral surface of the driven rod so as to screw the driven rod in the inner peripheral surface of the rotor. Further, a spline is formed in the outer peripheral surface of the driven rod in a state overlapped with the male thread, and a spline groove to be engaged with this spline is formed on the rotor side, and according to this structure, the driven rod is movable in a center axis direction but is not rotated about the center axis.
Patent Publication 1: Japanese Utility Model Laid-open Publication No. 6-53851
Patent Publication 2: Japanese Patent Laid-open Publication No. 6-300106